coelenterate

Jellyfish, hydra, sea anemones, and corals {coelenterate}| {cnidaria} are Ecdysozoa protostomes, live in ocean, and have radial symmetry.

digestion

They have mouths with tentacles that push food into mouth. Chemicals digest food in sacs, and then pseudopods from endoderm make food vacuoles.

tissues

Tissues are epithelial, connective, muscular, nervous, and reproductive.

senses

Hydra and jellyfish can sense mechanical, thermal, and chemical stimuli.

nervous system

Coelenterates were first animals to have neurons, synapses, and nerve nets, as well as specialized sense organs, but coelenterates have no organized interneurons or ganglia.

Both neural and non-neural cells transfer electrical signals by electrotonic coupling, with no chemical synapses.

In hydra, mechanical stimulation releases acetylcholine, epinephrine, norepinephrine, serotonin, and histamine transmitters from neurons, which discharge nematocysts.

classes

Classes are watery hydroids or hydra (Hydrozoa), flowery anemones and corals (Anthozoa), and bowl-shaped jellies (Scyphozoa). Corals and anemones are polyploid and stationary. Bases are downward, and tentacles and mouth are upward. Jellyfish are medusoids, swimming with tentacles and mouth downward.

colonies

Portuguese man-o'-wars bud on top of each other to make colonies.

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Date Modified: 2022.0224